波束方向探测技术的注入式仿真系统验证

这篇文章主要介绍采用功率探测仪方式的注入式仿真系统对波束方向地面探测试验系统进行验证的系统设计和软、硬件控制与实现。通过向注入式仿真系统输入模拟目标星在不同位置发射的信号功率,以及目标星在平台坐标下的角度和位置信息,一方面确定地面探测试验系统技术方案的可行性和检测相关设备的性能,另一方面验证对目标星发射天线主波束方向的探测是否满足精度要求。通过仿真试验证明该注入式仿真系统不仅使用方便、节约成本,而且通过控制相关仪器设备能够准确记录地面探测试验系统对目标星仿真数据的计算信息,进而实现验证。     

Electron Beam Optics System PIC Simulation for MMW TWTs

The basic feature and design method of MMW TWTs electron optics are analyzed in this paper. With the increasing area convergence ratio of the electron gun in TWTs, the initial thermal velocity of electrons at cathode and the non-magnetic shielded effect can no longer be neglected. It brings new challenge for the design and simulation of MMW TWTs electron optics. A method of investigation the beam DC characteristics is described using particle-in-cell (PIC) simulation and incorporate electron beam optics model integrated electron gun with periodic permanent magnetic focusing system. It is valuable for achieving the goal of first-pass design success and the electron optics engineering design and optimization.     

CSRe减速模拟

对兰州重离子加速器冷却储存环实验环中束流的减速过程进行了模拟研究,采用变换谐波的方式将粒子减速到较低能量,以适应高精度原子物理实验的需要.根据模拟结果得到了减速过程各个时刻粒子在纵向相空间分布,并给出了高频参数在减速过程中的变化曲线.     

Parallel Supercomputing PC Cluster and Some Physical Results in Lattice QCD

We describe the construction of a high performance parallel computer composed of PC components, present some physical results for light hadron and hybrid meson masses from lattice QCD. We also show that the smearing technique is very useful for improving the spectrum calculations.     

Parallel Supercomputing PC Cluster and Some Physical Results in Lattice QCD

We describe the construction of a high performance parallel computer composed of PC components, presentsome physical results for light hadron and hybrid meson masses from lattice QCD. We also show that the smearingtechnique is very useful for improving the spectrum calculations.     

Construction and Application of a UHV Compatible Cluster Deposition System

The design and operation of a new UHV-compatible atomic cluster deposition system is described. The design is optimised for high cluster fluxes and for the production of cluster-assembled nano-devices. One key feature of the system is a high degree of flexibility, including interchangeable sputtering and inert gas aggregation sources, and two kinds of mass spectrometer, which allow both characterisation of the cluster size distribution and deposition of mass-selected clusters. Another key feature is that clusters are deposited onto electrically contacted lithographically defined devices mounted on an UHV-compatible cryostat cold finger, allowing deposition at room temperature as well as cryogenic and elevated temperatures. In-situ electrical characterisation of cluster-assembled devices can then be performed in the temperature range 1.2--75 K.     

OLEDs瞬态延迟时间的模拟及在信号通讯的应用

基于有机发光二极管的电致发光原理,建立了载流子注入延迟时间和发光延迟时间模型,探索了延迟时间的影响因素,发现发光延迟时间与器件有效面积、器件厚度、外加电压等密切相关。通过制备不同面积的OLED器件,发现器件面积越小,发光延迟时间越短。以高速信号激励不同面积的OLEDs器件,面积为0.01 mm2的器件能够实现1 000 Mbit/s的信号传输速率,且能量利用率达到47.7%。     

W–band光注入器的模拟研究

模拟研究了1.6个腔、高梯度的W-band光阴极微波电子枪系统,该系统能产生和加速300pC的电子束团.设计系统由频率91.392GHz光阴极微波电子枪以及频率91.392GHz行波加速结构组成.基于射频直线加速器标度律与数值模拟结果,设计系统能产生能量1.74MeV,电量300pC,束团长度0.72ps,归一化横向发射度0.55mm·mrad的电子束团.研究了高频、高梯度下的束流动力学.由于高梯度,有质动力效应在束流动力学中起重要作用,且由于横向与纵向之间的耦合,在基次空间谐波的情形下,仍然存在着有质动力聚焦效应.     

Soft modes in ferroelastic LaP5O14 and NdP5O14

We have observed an underdamped, temperature dependent optical phonon in the non-polar ferroelastic compounds NdP₅O₁₄ and LaP₅O₁₄. These materials exhibit a second-order displacive phase transition from C_2h to D_2h point group symmetry at temperatures slightly above ambient. The soft mode is observed in both phases.     

空间滤波技术在激光照射测量系统中的应用研究

提出了运用针孔光阑来提高细长柱形物边缘检测精度的方法。通过在聚焦透镜后焦点处加一针孔光阑进行低通空间滤波,滤除掉柱形边缘直边衍射的高频成分,以提高边缘检测精度。理论上分析了该方法的可行性,并通过实验对结论作出了验证。     

HIRFL装置主动式点扫描束流配送系统的Monte Carlo模拟优化

为获得适用于HIRFL 装置主动式点扫描束流配送系统配送的碳离子束,利用Monte Carlo (MC) 工具SHIELD-HIT12A 研究了配送距离和微型脊形过滤器结构周期对治疗室等中心处束斑半高宽(FWHM) 和剂量平坦度的影响。模拟研究发现:束流配送距离越短,束斑FWHM越小,但剂量平坦度越差;微型脊形滤器结构周期是影响剂量平坦度的关键因素,周期越小,剂量平坦度越好。通过模拟研究得出:在HIRFL装置重离子治疗终端将真空窗设置在距等中心距离小于125 cm 时,采用结构周期为2 mm微型脊形过滤器可以满足主动式点扫描照射对束斑FWHM和剂量平坦度的要求。To obtain carbon ion beams suitable for the active spot scanning beam delivery system at the Heavy Ion Research Facility in Lanzhou (HIRFL), the Monte Carlo program SHIELD-HIT12A was used to study the influences of beam delivery distance and structure period of mini ridge filter on full width at the half maximum (FWHM) of beam spot and dose flatness at the isocenter of the treatment room. The present simulation study shows that the shorter was the beam delivery distance, the smaller was the FWHM of beam spot, but the worse was the dose flatness. The structure period of mini ridge filter was a key factor to account for the dose flatness at the isocenter. The smaller was the structure period of mini ridge filter, the better was the dose flatness. Based on the simulation results, we conclude that 2 mm structure period for a mini ridge filter statisfies the requirements on the FWHM of beam spot and dose flatness at the isocenter for the active spot scanning beam delivery system at HIRFL when the distance between the vacuum window and the isocenter is set shorter than 125 cm in the nozzle.     

BEPCⅡ束流损失探测系统及其初步应用

束流寿命是衡量储存环性能的重要参数,它直接影响到储存环能否正常运行.采用束流损失探测系统通过探测束流损失的地点,可以为分析束损原因、优化机器参数和提高束流寿命提供依据.介绍了北京正负电子对撞机重大改造工程(BEPC Ⅱ)束流损失探测系统的基本情况:前端束流损失探测器输出的脉冲信号送到下位机进行处理,通过CAN总线将所有的下位机连接到位于本地站的前端PC机,此PC机再通过以太网与中控室的PC机或工作站进行数据通讯,最终实现对束流损失的实时监测、数据存储,并能对历史数据进行处理,达到实时显示全环束损分布的目的.文章最后还简要介绍了整个系统在BEPC Ⅱ调束过程中的初步应用.     

Computer Simulation of an Ion Beam Antenna

The feasibility of using a modulated beam of ions as an antenna in the magnetosphere is discussed briefly. A computer simulation of an ion beam in a plasma is presented in which the motion of the ions is prescribed while the electrons in the surrounding plasma are represented by concentric charged shells, each of which moves in the self-consistent field set up by the beam and the other shells. By following the motion of the shells on a computer, an attempt is made to estimate the sheath current that is induced in the plasma by the beam.     

铝原子团簇Al5、Al5-和Al5+稳定结构的密度泛函理论研究

采用密度泛函理论的四种方法 :杂化密度泛函B3LYP与B3PW 91、Perdew Wang91交换与相关泛函WP91PW91、局域自旋密度近似SVWN ,研究了Al5、Al5-和Al5+ 团簇的多种可能结构 ,找到了它们稳定的结构与自旋态 ,与已有的理论结果作了比较 ,并计算了Al5-的绝热与垂直电子离解能、Al5的绝热与垂直电离势 ,同有关的实验数据比较 ,符合较好 .同时对四种密度泛函方法的计算结果作了一些比较与讨论     

Application of a DPC for PMD Compensation in Environmental Perturbed Transmission System

Polarization mode dispersion (PMD) compensation is presented on environmental perturbed fiber-optical transmission system in this paper. We achieve a dynamic polarization controller (DPC) to feedback control the PMD, successfully.     

双圆筒加速透镜中强流束传输的模拟

用矩阵法分析非强流束流与强流束流在双圆筒加速透镜中的传输,编写束流在双圆筒加速透镜等元件中传输的计算程序DCALENS.采用优化方法实现给定的光学条件,用迭代方法计算强流束传输获得自洽解.在不同束流流强条件下,用DCALENS程序进行模拟计算,并对模拟结果进行比较分析.结果表明:束流流强越大,束流包络曲线横向发散越显著,空间电荷力越强;束流流强大于2 A时,束流包络曲线发散明显.